Screening Tests For Your Pregnancy

The vast majority of babies conceived are healthy. As a women, and to a lesser extent, a man, becomes older, the risks of problems with their baby increases.

The main concern, which in itself is uncommon, is the risk of Down Syndrome. In this condition, the fetus has an extra chromosome 21 and is born with intellectual challenges and often physical health problems.​To confirm that your baby doesn't have particular conditions there are a number of screening test options. Screening tests give an estimate of the likelihood of a problem being present in your pregnancy. In general, the risk is said to be 'low' or 'high', rather than giving a definite 'yes' or 'no'. Tests that give a 'yes' or 'no' are called diagnostic tests.

First trimester combined screen.This is the tradition screening test for Down Syndrome and has been available for many years. This test is based upon maternal age, hormone levels from maternal blood taken at approximately 10 weeks gestation, and an the ultrasound measurement of nuchal translucency (neck skin thickness) measured at 12-13 weeks. The result received is an estimate of the risk in the pregnancy of that baby having a chromosomal abnormality of chromosomes 21 (Down syndrome), 13, or 18. If the result indicates a high risk, parents may then choose to have confirmation by obtaining fetal DNA. This has in the past been achieved by either CVS (placental sampling at 12-13 weeks), or amniocentesis.Your obstetrician will help explain the significance of the result, which almost always provides reassurance that your baby is healthy.

NIPS (non invasive prenatal screening).Recently there have been significant advances in the way we can obtain fetal DNA. It is now possible to simply take blood from the pregnant mother anytime from 10 weeks on, and to obtain small fragments of fetal DNA which are floating in her bloodstream. These can then be tested for a large number of abnormalities including all of those mentioned above, along with a number of other less common syndromes. The test has been termed NIPS (non-invasive prenatal screening), and as it is DNA based the result is overwhelmingly more reliable than that obtained from first trimester combined screening.NIPS has dramatically reduced the number of women requiring CVS and amniocentesis. A number of women are also choosing to have this test first up, rather than undergoing the more traditional first trimester combined screen. Of course there is a cost for this, and at the moment the blood is sent to America for testing. If you do choose to have NIPS then we would also recommend a 12 week ultrasound to pick up anatomical problems which are not tested for using NIPS.At present the test is about twice the cost of the combined screen, and the results take 2 weeks to become available.Your Obstetrician will discuss which of these screening tests are best for you.In general, women over 40 years of age or those who have a higher risk for other reasons, probably should consider NIPS, and women with lower risk may choose to have the cheaper & quicker combined screen.

Diagnostic tests for your pregnancy.Diagnostic tests will give a 'yes' or 'no' answer regarding whether your baby has a particular health issue. The diagnostic tests are CVS (chorionic sampling) or amniocentesis.These tests involve taking a sample from the placenta or from the fluid around the baby to check the chromosomes of the baby. They almost always provide a definite answer regarding the baby's chromosomes.Diagnostic tests require insertion of a needle into the uterus, and do carry a 0.5% to 1% risk of losing the pregnancy. Hence, you will be provided with all the relevant information regarding risks and benefits before deciding to have this test.

18-20 week Mid trimester Ultrasound.This ultrasound assessment allows an ultrasound specialist to carefully check your baby’s structure and organ development is normal.You will be referred to one of our local Ultrasound service providers for the test.Most problems detected are minor, and if further assessment or advice is needed, your obstetrician will give you guidance.An opinion from an ultrasound subspecialist in Melbourne will be sought if there are concerns on the first scan.